Poor OpenGL quality on Mac OS 10.5.8, even demos

[MattPhillips]

Hi,

I'm finding that on the Mac, under Qt (4.5, 4.6) everything is rendering very slowly and textures are oddly distorted--as though the viewport sides had been expanded each by 2x and the actual screen occupied the upper left-hand quadrant. You can see what I'm talking about with the attached screenshot from the 'HelloGL' demo--note the position of the central 'Qt'. Also, QGLFormat won't accept the QGL::StereoBuffers flag--the graphics fail completely if I include that. I don't have these problems with Ubuntu. Anyone know how I can fix this? Thank you!

Matt